1. Field of the Invention
The present invention relates to orthodontic appliances, and particularly to intraoral components of orthodontic headgear such as the inner bow of a double facebow utilized to exert a rearward force on orthodontic elements secured to the teeth.
2. Prior Art
The principal objective of orthodontic treatment is to alter the relationship of teeth so as to provide proper relative disposition and articulation of the teeth in the upper and lower jaws. In order to accomplish this objective, it is desirable in many instances to apply an external force to an intraoral component of headgear, which component is attached to teeth, usually those of the upper jaw, and more particularly to upper molars.
A conventional intraoral component for applying force to teeth in orthodontic treatment is a double facebow, including an inner bow having tips engageable in sockets of bands encircling molars and an outer bow extending outward of the mouth to which tension force can be applied. Such facebow is usually removable by the patient simply by disconnecting the force-supplying mechanism from the outer bow and pulling the inner bow out of the mouth without the necessity of disconnecting any securing element. Conventionally, the facebow applies rearward pressure to the molar bands by the tips of the inner bow exerting thrust on the sockets in which they are received. Such tips are straight, rather sharp wires.
Instances have occurred where the facebow has been pulled to withdraw the inner bow from the mouth without first disconnecting the force-applying mechanism, and the facebow has then been released resulting in the force-supplying means driving the facebow toward the face so that the tips of the inner bow are impelled toward the face with sufficient force to penetrate the flesh, or even the eyes, and cause injury. In addition to the inner bow of the face bow having ends in the form of sharp tips, such a facebow may have a sharp spur projecting inward from its central portion for engaging and lifting the central portion of the upper arch wire for intruding the front teeth.